Dermatology is the branch of medicine concerned with the skin, mucous membranes, hair, and nails – and the conditions that affect these. Skin is the largest organ in the body and plays a vital role in protecting against external threats, regulating body temperature, and providing sensory information.
Although the skin is a relatively easy organ to examine in most cases, there are more than 1,000 distinct skin diseases and many variants, which can lead to difficulties in diagnosis and treatment. Observation of the morphology, distribution, configuration, colour, surface, and secondary changes of the skin are useful in the diagnosis and selection of a treatment plan.
Dermatological conditions are very prevalent, accounting for approximately 15-20 per cent of general practice consultations, with these ranging from minor, self-limiting problems to conditions that can cause significant disability. The International Classification of Disease (ICD 10) lists over 1,000 skin or skin-related illnesses, but only a small number of these account for the majority of the disease burden. Dermatological conditions can be extremely debilitating and greatly impact the quality of life of patients.
Overview of dermatology
Dermatology encompasses a wide range of conditions, from common issues including acne and eczema to more complex and debilitating conditions such as skin cancer and autoimmune diseases. An overview of some of the common conditions in dermatology is outlined below.
Rosacea is a chronic inflammatory condition that is characterised by recurrent flushing, erythema, papules or pustules on the nose, chin, cheeks, and forehead. Permanent scarring, persistent erythema, and ocular sequelae can occur without prompt diagnosis and treatment. Rosacea is usually limited to the skin but there is an association of systemic comorbidities including neurologic diseases, inflammatory bowel disease, and cardiovascular disease, with psychological stress also associated with rosacea. Up to 75 per cent of patients with rosacea have ocular symptoms including dryness, redness, tearing, tingling, light sensitivity, and blurred vision. The aetiology of rosacea is not fully understood but genetics, immune reaction, environmental factors, microorganisms, neurovascular dysregulation, and ultraviolet (UV) exposure all thought to play a role. Diagnosis is generally based on clinical judgement, which can lead to many with mild disease being undiagnosed.
Acne vulgaris is a common chronic inflammatory skin disorder characterised by clogged pores leading to pimples, papules, and pustules. It primarily affects the face but can also affect the back, trunk, and upper arms. It commonly presents during adolescence but can affect individuals of any age. The prevalence of acne vulgaris is estimated to range from 35 per cent to as high as 90 per cent among adolescents. Severity of acne vulgaris can range from mild to very severe, characterised by disfiguring inflammation which can lead to scarring, hyperpigmentation, and adverse psychological stress. Acne develops as a result of hypersensitivity of the sebaceous glands to normal levels of circulating androgens, which can then be exacerbated by the presence of a bacterial species called cutibacterium acnes. There are several proposed contributory factors for acne, and these include excess sunlight exposure, medication use, oily cosmetics, use of occlusive wear, endocrine disorders, genetics, and psychological stress. Acne vulgaris is typically diagnosed based on physical examination rather than laboratory tests, unless underlying hyperandrogenism or other specific conditions are suspected.
Skin cancer is the most common cancer in Ireland and is classified into melanoma or non-melanoma. Melanoma is a cancer of the melanocytes – cells that make the pigment melanin. Melanoma is much less common than non-melanoma, but it is generally much more serious as it can metastasis to other organs in the body. Non-melanoma can be further classified into basal-cell carcinoma (BCC) and squamous-cell carcinoma (SCC). BCC originates in cells lining the bottom of the epidermis and accounts for approximately 75 per cent of all skin cancers. SCC originates in cells lining the top of the epidermis and accounts for approximately 20 per cent of all skin cancers. It is estimated that 90 per cent of skin cancers are caused from UV radiation from sun or sunbed exposure. Other risk factors include pale skin, age, smoking tobacco, immunosuppressant medication, and immunosuppressant conditions such as human immunodeficiency virus (HIV).
Skin cancers are often located on the head and neck regions, which are often the most sun-exposed regions on the body. The first symptom of a melanoma is often a new mole or a change in the appearance of an existing mole, consistent with the mnemonic ABCDE;
- Asymmetry: Usually asymmetrical with an irregular shape
- Borders: Usually an uneven, irregular border
- Colour: Usually a mix of colours
- Diameter: Usually larger than 6mm
- Evolving / Elevated: Usually changes over time and is usually elevated above the skin.
Melanomas can appear anywhere on the body but are more common in sun-exposed areas. The first symptom of non-melanoma cancer is usually the appearance of a lump or discoloured patch on the skin, which persists and slowly progresses over months or years. BCC often appears as a small and shiny lump, with a translucent or waxy appearance. The lump often grows and may become crusty, bleed, or develop into an ulcer. SCC often appears as a firm pink lump with a rough or crusted surface, with some scale. The lump is usually tender, bleeds, and may also develop into an ulcer. The first step in the diagnosis of skin cancer is by physical examination and the use of ABCDE. Confirmation of the diagnosis of skin cancer is generally by biopsy and histopathological examination. Other investigative tests including a computerised tomography (CT) scan, a magnetic resonance imaging (MRI) scan, a positron emission tomography (PET) scan, and blood tests may also be performed to confirm diagnosis or investigate metastasis.
Psoriasis is a chronic proliferative and inflammatory condition of the skin, characterised by erythematous plaques covered with silver or white scales. The plaques can present anywhere on the body, but the scalp, elbow, knees, and lower back are the most common parts of the body. Psoriasis can also affect the joints and eyes – with approximately 10 per cent having ocular involvement and nearly one in three patients having psoriatic arthritis. Psoriasis is often associated with psychological conditions, cardiovascular disease, and hepatic disease. The exact aetiology of psoriasis is unclear, but it is considered to be an autoimmune disease mediated by T lymphocytes. Genetics is suggested to play a strong role, while triggers of psoriasis can include certain medication, infection, psychological stress, alcohol, smoking, and obesity.
Dermatitis is a common condition, affecting approximately 20 per cent of people at some stage in their life
Diagnosis of psoriasis can usually be made by clinical morphology and site of lesions, while biopsy and histopathology may be required in some cases. Laboratory studies – including a full blood count, hepatic function tests, renal function tests, rheumatoid factor, and uric acid levels – may be useful. Differential diagnosis may be required to rule out conditions such as eczema, seborrheic dermatitis, and secondary syphilis, while referral to rheumatology may be necessary if psoriatic arthritis is suspected.
There are several subtypes of psoriasis, each with a different clinical presentation. Plaque psoriasis accounts for approximately 90 per cent of cases, which presents as red and dry plaques, covered in silver scales, and may be itchy and sore. Psoriatic arthritis is a form of inflammatory arthritis which affects approximately one in three of patients with psoriasis, involving inflammation of the joints. Inverse psoriasis presents in the creases of the skin, often in the armpits, under the breasts, groin, or buttocks. Pustular psoriasis is a rare form of psoriasis that is characterised by pus-filled pustules on the skin, while guttate psoriasis causes small (less than 1cm) sores, usually on the chest and back. Scalp psoriasis is characterised by red patches covered in thick silver scales on the scalp, causing severe itchiness and sometimes temporary hair loss.
Dermatitis is a group of inflammatory skin conditions, characterised by epidermal changes. Dermatitis is a common condition, affecting approximately 20 per cent of people at some stage in their life. Atopic dermatitis, also known as eczema, is the most common form of dermatitis and can affect both adults and children. The aetiology of atopic dermatitis is complex, with both genetic and environmental factors causing abnormalities in the epidermis and immune system. Environmental factors such as tobacco smoke, air pollutants, certain skin products, and certain foods can trigger or exacerbate atopic dermatitis. Common symptoms of atopic dermatitis include itching, skin redness, dry skin, weeping rash, and thickening of the skin. Complications of dermatitis can include bacterial infection, viral infections, psychological issues, and sleep problems.
Contact dermatitis is another common subtype of dermatitis, which presents with symptoms of skin redness, itchiness, burning, pain, and blisters. Allergic contact dermatitis occurs when an individual is exposed to an allergen that causes a hypersensitive reaction that involves the immune system. Irritant dermatitis occurs when an individual is exposed to an irritant for an amount of time sufficient to damage the outer layer of the skin. Other types of dermatitis include seborrheic dermatitis, photosensitive dermatitis, post-traumatic dermatitis, discoid dermatitis, eyelid dermatitis, and hand dermatitis. Diagnosis is usually made through a thorough physical examination and a complete medical history. Other investigative tests may be carried out in a differential diagnosis, while blood tests can check for an elevation in Immunoglobulin E (IgE).
Skin infections account for a wide variety of conditions that can range in severity from mild infections to serious, life-threatening infections. The clinical presentation and aetiology can vary in skin infections. Skin infections can be classified based on their level of complication or level of purulence. They can also be classified on what microorganism caused the infection – bacteria, fungus, or virus. Common skin infections include impetigo, cellulitis, folliculitis, shingles, chickenpox, ringworm, and athlete’s foot. Complicated infections can extend into the underlying deep tissue and include deep abscesses, necrotising fasciitis, and gangrene. These infections can present with features of sepsis. Risk factors for skin infections include increasing age, obesity, trauma, cardiopulmonary disease, and diabetes. Rapid diagnosis greatly improves clinical outcomes for patients, particularly in patients with severe infection.
Pharmacological treatment
There are a wide range of treatment options available for dermatological conditions. These options encompass topical agents, systemic treatments, and biologics. Topical agents used in dermatology usually contain corticosteroids, retinoids, or antibiotics. Systemic treatments are often utilised for more severe conditions or if the patient hasn’t responded to topical treatment. Antibiotics, corticosteroids, retinoids, immunosuppressants, and antihistamines are examples of systemic therapies. Biologics are advanced therapies that target specific areas of the immune system that are involved in inflammatory skin conditions.
Topical treatment
Topical agents are applied directly to the skin and include creams, ointments, gels, lotions, and solutions. Topical treatment options are often first-line treatment for many skin disorders.
Topical corticosteroids are commonly used to treat conditions such as eczema, psoriasis, and contact dermatitis. They reduce inflammation and itching, as well as slowing down the production of skin cells. Corticosteroids are classified based on their potency, with low, medium, and high potency all options to consider. Betamethasone and clobetasol are examples of high potency corticosteroids, fluticasone and mometasone are medium potency, and hydrocortisone is a low potency corticosteroid. Medium-to-high potency corticosteroids can be used to treat most areas on the body, including the trunk and extremities. These are useful in thick skin areas, particularly in psoriatic plaques. Topical corticosteroids used for the face, genitalia, or areas of thin skin should be either avoided or of lower potency and limited to short-term use. Potential adverse effects of topical corticosteroids are usually local and include bruising and thinning of the skin. Systemic adverse effects are rarer and could include hypertension, mood swings, weight gain, and Cushing’s syndrome.
Antibiotics, corticosteroids, retinoids, immunosuppressants, and antihistamines
are examples of systemic therapies
Topical calcineurin inhibitors are often used to treat eczema. They block the protein calcineurin, which is important in the activation of T-cells. Calcineurin inhibitors reduce the activity of T-cells to reduce the immune response, thereby reducing inflammation and itch. Topical calcineurin inhibitors are particularly useful to treat sensitive areas or if topical corticosteroids are ineffective. Tacrolimus is a calcineurin inhibitor used to treat eczema. Sensitivity to sunlight and skin irritation are two of the most common adverse effects. They can cause a burning or itching sensation when initiated but this generally resolves within a week.
Vitamin D analogues are another treatment option for conditions such as psoriasis as they reduce inflammation and slow the production of skin cells. Calcipotriol is a commonly used vitamin D analogue. Potential adverse effects are usually quite mild when used correctly and mainly include local skin irritation or burning. The efficacy of vitamin D analogues can be increased with combination therapy with topical corticosteroids or occlusion therapy. Combination therapy with calcipotriol and betamethasone is more effective than monotherapy and improves compliance in chronic psoriasis patients. Topical retinoids are vitamin A derivatives that are commonly used to treat dermatological conditions such as acne and psoriasis. Retinoids can regulate cell proliferation and increase collagen production. Isotretinoin and adapalene are commonly used topical retinoids. They can cause dryness of the skin and lips, photosensitivity, and can be teratogenic.
Topical antimicrobials can be used to treat a wide variety of skin infections. Topical antibiotics can be used to treat bacterial infections such as impetigo. Clindamycin is often used to treat acne, while metronidazole can be used to treat rosacea. Clotrimazole, ketoconazole, and miconazole are antifungals that are used topically to treat common fungal infections such athlete’s foot, ringworm, and yeast infections. Antiviral topical agents can be used to treat viral infections including herpes simplex and herpes zoster, with acyclovir commonly used.
Other topical agents are possible adjuncts to treatment. Emollients are an important aspect in the management of certain skin conditions and daily use is recommended. They can be applied liberally and help to hydrate the stratum corneum and improve the barrier function of the skin. Topical keratolytic agents, including coal tar and urea, can help exfoliate the skin and are used to treat psoriasis, warts, and hyperkeratosis.
Systemic treatment
Systemic treatment often involves the use of oral or injectable medications. They are often used for more severe conditions or treatments that have not responded to topical treatment.
Systemic retinoids are effective in treating dermatological conditions such as acne and psoriasis. They exert their mechanism of action by regulating cell proliferation. Acitretin is an oral retinoid used to treat severe psoriasis. Isotretinoin is used in severe acne that has failed to respond to topical therapy or systemic antibiotic treatment. Oral retinoids are teratogenic and caution should be taken in females of child-bearing potential. Strict birth control measures should be used during treatment. The most common adverse effects include sensitivity to sunlight and dryness of the skin, lips, nostrils, and eyes.
Immunomodulators, including methotrexate and ciclosporin, are used to treat some autoimmune dermatological conditions such as psoriasis and atopic dermatitis. Methotrexate reduces the activity of the immune system by inhibiting lymphocytes, through multiple mechanisms. Potential adverse effects include bone marrow suppression, nausea, hepatitis, and teratogenicity. Methotrexate is generally administered once weekly, while folic acid can be taken orally to reduce adverse effects. It can be administered orally, but subcutaneous injection increases bioavailability and reduces gastrointestinal side effects. Potential adverse effects include bone marrow suppression, nausea, hepatitis, and teratogenicity. Ciclosporin is a calcineurin inhibitor and works by reducing the activity of T-cells. Potential adverse effects include hypertension, arrhythmias, dyslipidaemia, increased risk of infection, increased risk of lymphoma, and decreased renal function.
Systemic corticosteroids can be given to reduce inflammation in some inflammatory skin conditions. Prednisolone is the most common corticosteroid administered orally. The use of systemic corticosteroids should be limited to occasions where other treatment options fail or due to both short-term and long-term adverse effects. Their use should be reserved for acute and severe exacerbations. Adverse effects of corticosteroid use can include Cushing’s syndrome, increased risk of infection, cardiovascular disease, and osteoporosis.
Antihistamines can be useful to suppress itch associated with certain conditions. Antihistamines can be administered orally or topically. Common examples include cetirizine, levocetirizine, fexofenadine, bilastine, and chlorphenamine. Antimicrobials are used to treat various skin infections. Oral antibiotics, including minocycline and doxycycline, are commonly used to treat bacterial infections such as acne and cellulitis. Antivirals and antifungals can be used to treat common viral and fungal infections.
Biologics
Biologics are large molecules that specifically target the immune system to modify disease. Biologics are immunomodulators that can be used to treat dermatologic conditions that have an autoimmune component. Psoriasis, psoriatic arthritis, and eczema are sometimes treated with biologics if other treatment options have failed or for moderate-to-severe disease. They target pro-inflammatory cytokines and have effectiveness in reducing symptoms in moderate-to-severe disease. They exert their mechanism of action in a number of different ways. Adalimumab, etanercept, infliximab, and certolizumab work by inactivating tumour necrosis factor-alpha (TNF?). Ustekinumab works by blocking Interleukin (IL) -12 and IL-23. Secukinumab and tildrakizumab exert their mechanism of action by blocking IL-23.
The choice of biologic should be taken by a specialist and tailored to the needs of the patient. This choice is influenced by disease phenotype, outcome of previous biologic treatment, comorbidities, dosing frequency, and lifestyle considerations. Biologics require subcutaneous or intravenous administration, and the patient should be tested for hepatitis and tuberculosis before initiating therapy. There are many adverse effects associated with biologic therapy and they can include fever, muscle aches, weakness, loss of appetite, nausea, vomiting, diarrhoea, and irritation at injection site. As they reduce the effect of the immune system, the risk of infection is increased. Furthermore, several biologics can also increase the risk of malignancies including Hodgkin and non-Hodgkin lymphoma, leukaemia, and non-melanoma skin cancer.
Janus kinase (JAK) inhibitors are small molecules that offer targeted treatment for inflammatory skin conditions. They inhibit cytokine activity and therefore modify the immune system. Tofacitinib and upadacitinib are JAK inhibitors licensed for use in Ireland. They are associated with a risk of serious infection and thromboembolic events and therefore should be used with caution in patients that have cardiovascular problems.
Preventive dermatology
Preventive dermatology involves educating patients about their skin and ways to prevent dermatological conditions and maintain healthy skin. Education of patients on their condition, triggers, and skincare practices is important in the prevention and management of skin conditions. Patients should be encouraged to make some lifestyle modifications to improve their skin health. Ensuring adequate hydration, a balanced diet, and appropriate stress management are important to promote good skin health. Regular skin examinations are important, with patients encouraged to self-examine and monitor changes in moles or skin lesions. A proper skin care routine based on an individual’s skin type, with appropriate cleansing and moisturising also plays a role in skin health. Finally, proper sun protection with the use of broad-spectrum sunscreen that protects against UVA and UVB, protective clothing, and shade should be encouraged.
Role of the pharmacist in dermatology
Pharmacists play an important role in the management of dermatological conditions. They have an expertise in medication management, patient education, and can work with other healthcare professionals to optimise patient outcomes. Pharmacists are drug experts and can review medication regimens to ensure appropriate treatment, monitor for drug interactions, and reduce adverse effects. Pharmacists also counsel patients on their condition, treatment options, and potential adverse effects to enhance patient education. Pharmacists can also counsel to ensure improved adherence to treatment. Poor adherence is often a barrier to achieving optimal clinical outcomes and pharmacists are well-placed to improve patient adherence. Pharmacists can also provide information on preventive measures that can improve overall skin health. Pharmacists are well-placed to collaborate with other healthcare professionals to offer a comprehensive and patient-centred management plan for their patients. Finally, pharmacists can monitor progress and provide follow-up to support patients to achieve optimal clinical outcomes and improve quality-of-life.
References upon request.
